1. Field of the Invention
The present invention relates to a cathode-ray tube used as a display device of a television receiver and the like, and the structure of a getter supporter used in a flat display device and its applications.
2. Description of the Related Art
In a cathode-ray tube (CRT), the degree of vacuum in the tube must be maintained below a specified decompressed pressure. For this purpose, after evacuating in the manufacturing process, a getter mainly composed of barium and the like contained in the tube is heated to evaporate, and the residual gas in the tube and the gas generated in the tube after sealing are absorbed thereby.
FIG. 1 is a sectional view showing a cathode-ray tube having a getter on the inner surface of a funnel.
In FIG. 1, reference numeral 10 is a cathode-ray tube, and a tube body thereof is formed of a panel 11 and a funnel 12 mutually fused or melt-bonded and a fluorescent screen is formed by coating a fluorescent material on the inner surface of the panel 11.
Closely to the fluorescent screen, an aperture grille of a color selection electrode is disposed, and is supported by a frame 13. The frame 13 is fixed to panel pins buried in the panel 11. The frame 13 further is attached with an internal magnetic shield 14 to prevent effects of earth magnetism. Moreover, an electron gun 15 is accommodated in the neck portion of the funnel 12.
The cathode-ray tube 10 having such constitution is electrically sealed while evacuating the gas in the tube after the above parts to be disposed the tube are attached. The degree of vacuum in the tube at this time is about 5xc3x9710xe2x88x925 torr, but it is not enough for operating the cathode-ray tube 10 normally, and therefore a getter 30 is preliminarily sealed in the tube in order to further enhance the degree of vacuum so as to be lower than 5xc3x9710xe2x88x925 torr.
The getter 30 is affixed to the tip end of a getter supporter 20 attached to an anode button 16 of the funnel 12, and is disposed closely to the inner surface of the funnel 12.
As the getter, generally, a mixture of BaAl4 alloy and Ni is used. In the getter flashing process, after evacuating and sealing electrically, this getter is heated by induction from outside by using a high frequency coil. At this time, at the getter temperature of 800 to 840xc2x0 C., an exothermic reaction (thermite reaction) takes place, and this reaction heat is added to elevate the temperature quickly, and Ba begins to evaporate (dissipate) at 1130xc2x0 C., and the temperature rise of the getter 30 further continues up to 1300xc2x0 C.
Therefore, in this cathode-ray tube 10, by heating the getter 30 and dissipating its vapor, the gas within the tube is securely absorbed and adhered, so that a necessary degree of vacuum is maintained, and lowering of electron emission performance of the cathode is prevented.
FIG. 2 is an explanatory diagram in which a getter is mounted on a funnel by using a conventional getter supporter.
In FIG. 2, reference numeral 20 is a getter supporter, and a getter holder 22 and a contact support part 24 are provided at its tip end. The getter 30 is a thin disk-shape, and it is welded and affixed to the getter holder 22.
A mounting unit 21 of the getter supporter 20 is press-fitted and fixed to a bump of an anode button 16 provided at a specified position of the funnel 12.
The getter 30 is supported by the contact support part 24 by keeping a proper distance of 3 to 5 mm from the glass surface of the funnel 12 so as to be induction-heated by a high frequency coil. In order that this contact support part 24 may not floated from the glass surface of the funnel 12, a spring 23 is given with an adequate spring property so that an adequate spring pressure may be applied to the contact support part 24.
FIG. 3 is a magnified sectional view showing the contact support portion 24 of the conventional getter supporter 20.
As shown in FIG. 3, in the conventional getter supporter 20, the contact support portion 24 contacting with the glass surface of the funnel 12 is designed to support the getter 30 nearly at the central position of the getter 30. Accordingly, it is possible that the temperature rise of the getter 30 may be directly transmitted to the glass surface of the funnel 12, and hence there is a fear that fine glass cracks and the getter supporter deformation may occur.
Also in the conventional getter supporter 20 as shown in FIG. 3, since the getter supporter 20 has the spring property so that the contact support portion 24 may not float above the glass surface of the funnel 12, the high temperature of the getter 30 is transmitted to the getter supporter 20 when flashing the getter 30. When the spring pressure of the getter supporter 20 is too strong, the getter supporter 20 is likely to be deformed by its pressure and heat.
FIG. 4 is a diagram showing a modified example of a conventional getter supporter. The deformation of the getter supporter 20 varies with the heat resistance of the supporter, and the temperature and the pressure applied to the supporter (especially near the getter).
FIG. 5 presents a graph showing the relation between the spring pressure and the heat applied to the getter supporter and the amount of its deformation.
In FIG. 5, a line A and a line B show modified examples of the conventional getter supporter. As shown in the line A or the line B, when the spring pressure of the getter supporter is increased, the deformation of the getter supporter is increased accordingly.
In the conventional getter supporter, in order to keep constant the distance between the glass surface of the funnel glass and the getter, it is designed to support the getter nearly at the central position of the getter. It brings about the following two problems.
1. For getter flashing, the getter is heated at a high temperature from outside of the funnel glass by a high frequency, and the temperature of the getter at this time reaches as high as about 1300xc2x0 C. as the reaction heat is added, and this heat is conducted to the contact support portion. Therefore, if the distance between the getter and the contact support portion is short, the temperature of the funnel glass contact portion becomes high, and unfavorable fine glass cracks may be formed.
2. If the contact support portion of the getter supporter is floated from the funnel glass, contact vibration noise may be generated when subjected to vibration or impact. To prevent this, an adequate spring pressure is applied to the contact support portion, but if this spring pressure is too strong, the getter supporter is likely to be deformed by the heat at the getter flashing.
The present invention is devised to solve such problems of the conventional getter supporter, and its object is to present a display device and a getter supporter having such a structure so as not to cause any glass or crack cause deformation of getter supporter by the heat at the getter flashing.
A cathode-ray tube of the present invention comprises a getter supporter which has a mounting portion to be fixed to the inside of the cathode-ray tube at one end thereof, a getter holder for holding a getter at the other end thereof, and a spring portion for connecting the mounting portion and the getter holder, in which a getter supporter is provided with a contact support portion contacting with the inner surface of the funnel on the spring portion at a position spaced apart in the longitudinal direction from the holding position of the getter.
A getter supporter of a cathode-ray tube of the present invention comprises a mounting portion to be fixed to the inside of the cathode-ray tube at one end thereof, a getter holder for holding a getter at the other end thereof, and a spring portion for connecting the mounting portion and the getter holder, in which a contact support portion contacting with the inner surface of the funnel is provided on the spring portion at a position spaced apart in the longitudinal direction from the holding position of the getter. Accordingly, fine cracks of the funnel glass due to heat generation of the getter at getter flashing and heat generation of the contact support portion due to the high frequency for heating can be prevented, and also deformation of the supporter by the heat conducted to the contact support portion and the spring pressure can be prevented.
A getter supporter of a flat display device of the present invention comprises a mounting portion to be fixed to the inside of the device at one end thereof, a getter holder for holding a getter at the other end thereof, and a spring portion for connecting the mounting portion and the getter holder, in which a contact support portion contacting with the panel glass is provided on the spring portion at a position spaced apart in the longitudinal direction from the holding position of the getter. Accordingly, fine cracks of the panel glass due to heat generation of the getter at getter flashing and heat generation of the contact support portion due to high frequency for heating can be prevented, and also deformation of the supporter by the heat conducted to the contact support portion and the spring pressure can be prevented.